Safety switch



Nov. 29, 1932. B. w. BELL 1,889,344

SAFETY 'swITcH Filed Sept. 29, 19.30 2 Sheets-Sheet l Nov. 29, 1932. e. w. BELL. 1,889,344

SAFETY SWITCH Filed Sept. 29, 1950 2 Sheets-Sheet 2 Patented Nov. 29, 1932 PATENT OFFICE BENJAMIN W. BELL, F ST. LOUIS COUNTY, MISSOURI SAFETY SWITCH Application led September This invention relates to safety switches of a type which have particular utility in ignition system of aircraft.

One of the objects of this invention is to provide a safety switch responsive to the ignition switch which will cut out the supply of electricity from the battery.

Another object of this invention is to provide a lire-proof unit containing a battery and a safety switch mechanism so arranged that all current from the battery will be cut oil' upon the openinfr of the ignition switch.

Another object o-I the invention is to provide an improved circuit breaker. 15 @ther and specilic objects of this invention will be apparent from the following detail description taken in connection with the accompanying drawings.

F ig. 1 is a circuit diagram of the system.

2 is a plan view of the device with the cover removed.

F ig. 3 is a vertical section of the device.

The electric diagram may irst be eX- plained. Leads 1 and 2 are connected to a battery 3 and terminate respectively at the switch contacts 4 and 5. A two-blade knife switch is provided, of which a blade 6 is adapted to engage the contact 4 and a blade 7 is adapted to engage the contact 5. Switch terminals 8 and 9, on which the blades are pivotcd, are connected, respectively, to the wires 10 and 11, which are secured, respectively, to the posts 12 and 13. The wires 10, 11, are adapted to carry current for a utility circuit.

A wire 1a is connected to the terminal 8 and a wire 15 is connected to the terminal 9. rlhe other end of the wire 15 is connected to one side of a solenoid 16, and a wire 17 is connected to the other side of the solenoid. The wires 14 and 17 are secured, respectively, to posts 18 and 19, to which may be attached, respectively wires 18ul and 19a leading to an ignition switch 33.

45 The ignition switch of an airplane is arranged in such a manner that when the ignition is oil the leads are short circuited. It is the intention to connect the wires 18a and 19a to the ignition switch in such a manner that 00 when the ignition switch is oil the wires 18a 29, 1930 Serial No. 485,120.

and 19a will be short circuited. One of these wires, 1S@ as shown in the drawings, is attached to the ground plate of the switch 33 and the other wire, 19a as shown in the drawings, is attached to a terminal usually provided for a connection with a booster magneto which, however, is not used or required when a battery system is used.

A bar 20 is non-conductively connected to the blades 6 and 7 of the switch, and a plunger 21, having' a knob is connected to the bar 2G and is adapted by manual engagement with the knob to close the switch.

A latch member 23 is adapted to engage in a notch 24e and thus latch the switch in closed position. A spring 25 normally holds the latch in engaging position, but the arrangement such that the solenoid 16 will withdraw the latch from the notch 24 and thus when current is passing through it, that is through the wires 15, 17 by short-circuiting the line through the switch 33, the latch 23 will be withdrawn and the blades 6 and 7 will be opened by resilient means which will hereaiter be described.

A case 233, having a cover 2"?, enclose-s vthe battery 3 as well as the switch elements and the wires and leads hereinabove described. The posts 12, 13, 18 anc 1Q pass through and are secured to the walls of the case 2S and provide means for attaching circuit wires at points outside the case. A plunger 21 passes through a wall ci' the case with the knob 22 on the outside of the case for convenient manual manipulation. lllalls 28 and 29 are `provided inside the case for supporting the mechanism. A spring 30 is placed about the plunger 21 and on one end bears against bracket 31 and on the other end against a collar 32 secured to the plunger 21. n

By providing the structure described, it is contemplated that the wires leading to the ignition switch be attached to the posts 18 and 19. Upon turning the ignition switch to n break the ignition circuit, the wires 18a and 19a will be short-circuited and a magnetic field will be induced in the solenoid 16, thus withdrawing the latch 23 and thereby releasing the plunger n1 and permitting the switch 6,7 to be opened due to the action of the spring 30. The circuit connected to the posts 12 and 13, as well as the circuit connected to the posts 18 and 19, will be dead until the switch has been reset. This resetting may obviously be accomplished by pushing in the plunger 2l.

The arrangement is such that when the'ignition switch is oil', that is, when it has shortcircuited the wires 18a and 19a, there are no points outside the case 26 from which an electrical connection, accidentally or otherwise, may be made and the danger of lire from electrical causes when the ignition is oil is entirely eliminated.

lt is obvious from the foregoing description that the objects of the inventionhavebeen accomplished. Parts of the invention may be without the whole, and various changes nay be made in the details of construction, within the scooe of the appended claims, without departing from the spirit of this invention.

claim:

l. i device of the class described including a battery, a service circuit from said b-attory, a closed switch in said service circuit, an ignition switch, and means under the influence ol: the ignition swicch adaptedto automatically open closed switch upon the operation of the g ition s .vitch to ofil position.

2. A device of class described including a battery, a service circuit, a closed switch in said cir uit, solenoid, an ignition switch, and me used una

as unc the influence of the solenoid ntcd to open closed switch upon the operation of the ignition switch to oil position.

8. i device o the class described includg a battery, a pair of leads for said battery, plurality of circuits connected in parallel o said leads, closed switch controlling said leads, and means under the inlluence of one or said circuits adapted to open the switch upon the closing of said circuit.

device oi the class described includa battery, a closed switch, a plurality of circui connected in parallel and controlled tch, solenoid in series in one of i n s, and means under the influence of said solenoid adapted to open the switch upon closing ot the last named circuit.

i W-:ice of the class described includsed switch, an operating i circuit connected in parflled by said switch, and means eration with said plunger adapted to move the switch from closed to open position, a

latch adapted to cooperate with the plunger to hold the switch in closed position, and a solenoid in the operating circuit and positioned and adapted when under the influence of current passing through the operating circuit to withdraw the latch from engaging position.

7. A device of the class described comprising a closed case, an electric battery within the case, a service circuit from the battery, a switch in said circuit, means operable manually from the exterior of the case 'for closf ing said s vitch, means for maintaining said switch closed, and means adapted to cause the opening of the switch upon the operation of ignition means.

8. A device of the class described comprising a closed case, a battery within said case, a circuit from the battery, a switch in said circuit, means external or said case adapted for manual engagement to close the switch, a solenoid in said circuit, and means under the influence of said solenoid adapted to open the switch upon the closing or" the circuit.

9. A device of the class described com rising a closed case, a battery, a switch, an operating circuit and a utility circuit connected in parallel and controlled by said switch, moans for manual engagement exterior of the case for closing the switch, and means under the influence or' tl e operating circuit adapted to open the switch upon the closing of the ignition circuit.

l0. A device or" the class described comprising a closed case, an electric battery within the case, a service circuit from said battery, a switch controlling said circuit, a plunger passing through a wall of the case and adapted by ymanual engagement exterior oi' the case to close the switch, resilient means adapted to move' the switch from closed to open position, a latch adapted to engage the plunger and to hold the switch in closed position, and a solenoid connected through said switch adapted to release the latch from engaging position.

ll. A device of the class described comprising a closed case, an electric battery within the case, a service circuit from the battery, a switch in said circuit, means operable manually from the exterior of the case for closing said switch, means for maintaining said switch closed, and automatic means for opening the switch.

BENJAMIN WV. BELL. 

